Design Considerations for Equipment and Piping Layout: Guidelines for Vessels

Design Considerations for Equipment and Piping Layout:  Guidelines for Vessels

This is the first in a four-part series on equipment and piping layout. This article provides guidelines for equipment that includes tanks, horizontal and vertical vessels, cooling towers, and compressors.  The second article will discuss layout considerations for pumps. Guidelines for piping layout and pipe racks will be discussed in the third article.  The series concludes with the special requirements that process engineers apply to heat exchangers, valves, and instrumentation.

Where are you going to put that tank?

In real estate, the most important thing is location, location, location. When planning the layout of process and industrial equipment, every component’s exact location is important for many reasons. Some primary considerations are safety, maintenance, industry practices, costs, and ease of operation.

Many plants have their own specifications that can influence equipment layout. Industry-accepted guidelines must be considered, such as those from API, the Hydraulic Institute, and Global Asset Protection Services LLC.  Equipment suppliers may also have requirements that must be met for warranties.

Here are some general vessel and equipment layout guidelines to keep in mind:

• When practical, align the equipment and piping symmetrically to provide an organized appearance. For example, tanks and other vessels can be located in rows that allow pipe racks to be placed between rows.
• Consider arranging equipment to align with the process flow. This can optimize piping runs and even take advantage of gravity.
• Take thermal expansion into account. Make sure that vessels containing hot materials have room to grow.
• Provide enough space between each piece of equipment to provide appropriate access for operations and maintenance. A minimum of 3 feet of clear space is often sufficient.
• If mobile equipment is required for maintenance and servicing, make sure that it can move safely without hitting other equipment or piping that is on the ground or in the air.
• Make sure that access is available for emergency response and fire-fighting.
• Provide clear access at grade level for vessels with removable internals, or that require regular loading and unloading (such as catalyst, resin, desiccant, salt, etc.). For example, fired equipment must have clear access for the removal of tubes, burners, fans, and other related components.
• Furnaces should be located upwind and away from the processing equipment. Related towers should be located near the furnace to minimize alloy piping lengths.
• Vessels may have elevation requirements to provide proper pump performance.

Different Vessels Have Different Needs

Vessels are key components in refineries and chemical processing facilities. Chemical changes occur in reactors. Separation takes place in fractionators and accumulators. Piping engineers may need to interface with process engineers to make it all fit together.

Vertical Vessels

Towers, columns, and fractionators are all vertical vessels. They have some common design needs:

• The first ladder from grade should be on the pipe rack side for easy access by the operator.
• Coordinate the platform and ladder locations with the piping and the clear-drop area.
• Provide davits and crane access for towers over 50 feet tall.

Horizontal Vessels

 Drums, receivers, and accumulators are examples of horizontal vessels:

• If the vessel elevation does not have pump performance constraints, then the elevation is determined by process requirements or piping layout.

• Blowdown and flare knockout drums should be located in a separate area of the unit—at least 25 feet from other process equipment, and 50 feet from fired heaters—to avoid fire-related problems.

• One end of the vessel will be designed as fixed and the other end as sliding so that foundations and piping saddles can be designed properly.

• Inlet and outlet nozzles should be located on opposite ends of the vessel.

Cooling Towers and Compressors

Cooling Towers should be installed with the short side facing the prevailing summer winds. This allows the long sides of the cooling tower to intake an equal amount of circulating fresh air. Also, they should be located so the spray is kept away from buildings other and equipment.

Cooling towers should be located near an access road for maintenance of pumps, chemical addition equipment, and screens. If made of combustible materials, they should be a minimum of 100 feet away from process units.

Compressors take relatively low-pressure vapors, compress them, and discharge them at a higher pressure. Compressors typically have auxiliary equipment such as intercoolers, knockout drums, lube and seal oil consoles. Compressors require platforms at operating levels, and are sometimes installed in a shelter.

Next time, we will look at layout considerations for pumps.

Matrix Technologies is one of the largest independent process design, power systems engineering, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about our manufacturing operations management capabilities and manufacturing process control solutions, contact Jeremy Runk, Department Manager of the Process & Electrical Design Department.

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